U.S. patent number 7,494,706 [Application Number 11/472,771] was granted by the patent office on 2009-02-24 for fuser member.
This patent grant is currently assigned to Eastman Kodak Company. Invention is credited to Nataly Boulatnikov, Jiann-Hsing Chen, Shyh-Hua E. Jao, Joseph A. Pavlisko.
United States Patent |
7,494,706 |
Chen , et al. |
February 24, 2009 |
Fuser member
Abstract
The fuser members of this invention include a core member that
includes a rigid outer surface. A resilient layer comprising an
elastomer is optionally disposed on the cylindrical outer surface
of the core member. A tie layer is disposed on the resilient layer
or the outer surface if no resilient layer is present, the tie
layer being made of fluoropolymers, fluoroelastomers, fluorocarbon
thermoplastic copolymers and mixtures thereof. An outer layer of
fluoropolymer resin made from polytetrafluoroethylene,
polyperfluoroalkoxy-tetrafluoroethylene, polyfluorinated
ethylene-propylene and blends thereof, is disposed on the tie
layer.
Inventors: |
Chen; Jiann-Hsing (Fairport,
NY), Pavlisko; Joseph A. (Pittsford, NY), Jao; Shyh-Hua
E. (Pittsford, NY), Boulatnikov; Nataly (Rochester,
NY) |
Assignee: |
Eastman Kodak Company
(Rochester, NY)
|
Family
ID: |
38833956 |
Appl.
No.: |
11/472,771 |
Filed: |
June 22, 2006 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20070298251 A1 |
Dec 27, 2007 |
|
Current U.S.
Class: |
428/339; 428/421;
428/422; 428/447 |
Current CPC
Class: |
G03G
15/2053 (20130101); G03G 2215/2048 (20130101); Y10T
428/31544 (20150401); Y10T 428/3154 (20150401); Y10T
428/31663 (20150401); Y10T 428/269 (20150115) |
Current International
Class: |
B32B
25/08 (20060101); B32B 25/20 (20060101); B32B
27/08 (20060101); G03G 15/20 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Zacharia; Ramsey
Attorney, Agent or Firm: Ruoff; Carl F.
Claims
It is claimed:
1. A fuser member comprising: a core member comprising a rigid
outer surface; a tie layer disposed on said outer surface, said tie
layer comprising a fluorocarbon thermoplastics random copolymer
having subunits of: --(CH.sub.2 CF.sub.2)x--, --(CF.sub.2
CF(CF.sub.3))y--, and --(CF.sub.2 CF.sub.2)z--, wherein x is from 1
to 40 or 60 to 80 mole percent, z is greater than 40 to no more
than 89 mole percent, and y is such that x+y+z equals 100 mole
percent; and an outer layer comprising fluoropolymer resin selected
from the group consisting of polytetrafluoroethylene,
polyperfluoroalkoxy-tetrafluoroethylene, polyfluorinated
ethylene-propylene, and blends thereof disposed directly on the tie
layer.
2. The fuser member of claim 1 further comprising: a resilient
layer comprising an elastomer disposed between the outer surface
and the tie layer.
3. The fuser member of claim 2, wherein said resilient layer
comprises a thickness of from 1 to 10 mm.
4. The fuser member of claim 2, wherein said resilient layer
comprises polymethyl siloxane rubber.
5. The fuser member of claim 1, wherein said tie layer comprises a
thickness of from 10 to 500 microns.
6. The fuser member of claim 1, wherein said outer layer comprises
polyperfluoroalkoxy-tetrafluoroethylene.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This application relates to commonly assigned, copending
applications filed simultaneously herewith: U.S. patent application
Ser. No. 11/472,918 "FUSER MEMBER", U.S. patent application Ser.
No. 11/472,888 "FUSING MEMBER", U.S. patent application Ser. No.
11/472,919 "METHOD OF MAKING FUSER MEMBER".
FIELD OF THE INVENTION
This invention relates to electrostatographic apparatus and coated
fuser members and methods of making coated fuser members, and in
particular, to a conformable roller which includes an outermost
fluoropolymer resin layer uniquely bonded to a silicone base
cushion layer by means of a fluoroelastomer layer. More
particularly, this invention relates to an improved multi-layer
coating for fuser members and the method of making the multi-layer
coated fuser members for oil-free color digital printing
application.
BACKGROUND OF THE INVENTION
Known to the electrostatographic fixing art are various fuser
members adapted to apply heat and pressure to a heat-softenable
electrostatographic toner on a receiver, such as paper, to
permanently fuse the toner to the receiver. Examples of fuser
members include fuser rollers, pressure rollers, fuser plates and
fuser belts for use in fuser systems such as fuser roller systems,
fuser plate systems and fuser belt systems. The term "fuser member"
is used herein to identify one of the elements of a fusing system.
Commonly, the fuser member is a fuser roller or pressure roller and
the discussion herein may refer to a fuser roller or pressure
roller, however, the invention is not limited to any particular
configuration of fuser member.
One of the long-standing problems with electrostatographic fixing
systems is the adhesion of the heat-softened toner particles to the
surface of a fuser member and not to the receiver, known as offset,
which occurs when the toner-bearing receiver is passed through a
fuser system. There have been several approaches to decrease the
amount of toner offset onto fuser members. One approach has been to
make the toner-contacting surface of a fuser member, for example, a
fuser roller and/or pressure roller of a non-adhesive (non-stick)
material.
One known non-adhesive coating for fuser members comprises
fluoropolymer resins, but fluoropolymer resins are non-compliant.
It is desirable to have compliant fuser members to increase the
contact area between a fuser member and the toner-bearing receiver.
However, fuser members with a single compliant rubber layer absorb
release oils and degrade in a short time leading to wrinkling
artifacts, non-uniform nip width and toner offset. To make
fluoropolymer resin coated fuser members with a compliant layer,
U.S. Pat. Nos. 3,435,500 and 4,789,565 disclose a fluoropolymer
resin layer sintered to a silicone rubber layer, which is adhered
to a metal core. In U.S. Pat. No. 4,789,565, an aqueous solution of
fluoropolymer resin powder is sintered to the silicone rubber
layer. In U.S. Pat. No. 3,435,500, a fluoropolymer resin sleeve is
sintered to the silicone rubber layer. Sintering of the
fluoropolymer resin layer is usually accomplished by heating the
coated fuser members to temperatures of approximately 500.degree.
C. Such high temperatures can have a detrimental effect on the
silicone rubber layer causing the silicone rubber to smoke or
depolymerize, which decreases the durability of the silicone
rubbers and the adhesion strength between the silicone rubber layer
and the fluoropolymer resin layer. Attempts to avoid the
detrimental effect the high sintering temperatures have on the
silicone rubber layer have been made by using dielectric heating of
the fluoropolymer resin layer, for example see U.S. Pat. Nos.
5,011,401 and 5,153,660. Dielectric heating is, however,
complicated and expensive and the fluoropolymer resin layer may
still delaminate from the silicone rubber layer when the fuser
members are used in high-pressure fuser systems. U.S. Pat. Nos.
5,547,759 and 5,709,949 to Chen, et al. discloses a method of
bonding a fluoropolymer resin to various substrate including
silicone via a layer of fluoroelastomer layer and fluoropolymer
containing polyamide-imide layer. But this requires a thin base
layer to prevent the degradation of silicone base cushion substrate
during the sintering process. U.S. Pat. Nos. 5,998,034 and
6,596,357 to Marvil et al. also discloses a multilayer fuser roller
having fluoropolymer coating on a compliant base layer. However,
this requires pre-baking steps in an infrared oven to prevent the
degradation of primer layer and silicone base cushion. In addition,
a fuser member made with a fluoropolymer resin sleeve layer
possesses poor abrasion resistance and poor heat resistance.
For the foregoing reasons, there is a need for fuser members and a
method of fabricating fuser members which have a fluoropolymer
resin layer, and a thick compliant layer or layers, exhibiting
improved adhesion between their constituent layers, improved
abrasion resistance, improved heat resistance and the ability to be
made more economically.
SUMMARY OF THE INVENTION
The fuser members of this invention include a core member that
includes a rigid outer surface. A resilient layer comprising an
elastomer is optionally disposed on the cylindrical outer surface
of the core member. A tie layer is disposed on the resilient layer
or the outer surface if no resilient layer is present, the tie
layer being made of fluoropolymers, fluoroelastomers, fluorocarbon
thermoplastic copolymers and mixtures thereof. An outer layer of
fluoropolymer resin made from polytetrafluoroethylene,
polyperfluoroalkoxy-tetrafluoroethylene, polyfluorinated
ethylene-propylene and blends thereof, is disposed on the tie
layer.
ADVANTAGES
The fuser members of this invention have good non-adhesiveness to
toner, abrasion resistance, heat resistance and adhesion between
the layers. There is little or no deterioration of the layers or of
the adhesion between the layers during the sintering step of the
process, because the fluoroelastomer layer, and fluoropolymer resin
layer have good heat resistance.
These and other features, aspects, and advantages of the present
invention will become better understood with regard to the
following description and claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a cross-sectional view of a fuser member in accordance
with the present invention.
FIG. 2 is a schematic cross-sectional view of a fusing apparatus in
accordance with the present invention.
For a better understanding of the present invention together with
other advantages and capabilities thereof, reference is made to the
following description and appended claims in connection with the
preceding drawings.
DETAILED DESCRIPTION OF THE INVENTION
Since sintering the non-stick perfluoroalkoxy-tetrafluoroethylene
(PFA) fluoropolymer resin top coat layer is usually accomplished by
heating the coated fuser member to temperature up to 400.degree.
C., it is highly desirable to provide a good insulation layer
between the non-stick fluoropolymer resin layer and soft, heat
unstable silicone rubber base layer. Attempts to avoid the
detrimental effect the high sintering temperature upon the silicone
layer have not been satisfactory and were complicated. Most
importantly, the additional tie layer between the fluoropolymer
resin topcoat layer and the compliant silicone substrate layer must
provide good bonding between these two layers under harsh stress
and elevated temperature conditions. Common problems seen were
delamination and wrinkling of the non-stick top coat layer.
The current invention provides a fuser member having a
fluoropolymer (fluoroelastomer or fluorocarbon thermoplastic
copolymer (FLC) or a mixture thereof) as a tie layer was found to
provide good adhesion between the non-stick fluoropolymer resin top
coat layer and the compliant silicone substrate layer. In addition,
the current invention comprising the fluoroelastomer or the
fluorocarbon thermoplastic random copolymer (FLC) is incorporated
with fluoropolymer resin fillers (PFA, FEP, PTFE etc.) to increase
the adhesion between the fluoropolymer resin outer layer and the
tie layer are achieved by high temperature sintering process. This
also strengthens the adhesion to adjacent silicone layer and
prevents the degradation of the silicone base cushion layer under
high temperature applications, such as, external heated
conditions.
The fuser member of this invention comprises, in order,
a core member comprising a cylindrical rigid outer surface;
a resilient layer disposed on the cylindrical outer surface
comprising an elastomer;
a tie layer disposed on said resilient layer, said tie layer
selected from the group consisting of fluoropolymers,
fluoroelastomers, fluorocarbon thermoplastic copolymers and
mixtures thereof; and
an outer layer comprising fluoropolymer resin selected from the
group consisting of polytetrafluoroethylene,
polyperfluoroalkoxy-tetrafluoroethylene, polyfluorinated
ethylene-propylene, and blends thereof disposed on the tie layer a
support; a fluoroelastomer layer. In preferred embodiments of the
invention, the bonds between the fluoropolymer resin layers, primer
layers and fluoroelastomer layers are very strong, making it very
difficult to peel the layers apart.
In all embodiments, inventive rollers are preferably cylindrically
symmetrical, i.e., a cross-section of the roller taken at a right
angle to the roller axis anywhere along the length of the roller
has radial symmetry around the roller axis. The length of the
roller thereof determines the range of the printing width of the
substrate.
Although not explicitly disclosed in the preferred embodiments, it
will be understood that an optional supplementary source of heat
for fusing, either external or internal, may be provided, directly
or indirectly, to any roller included in a fusing station of the
invention.
FIG. 1 shows a cross-sectional view of a fuser member 110,
according to an embodiment of the invention, of which the
applications include fuser rollers, pressure rollers, and oiled
donor rollers, etc. The generally concentric central core or
support 116 for supporting the plurality of the layers is usually
metallic, such as stainless steel, steel, aluminum, etc. The
primary requisite for the central care 116 materials are that it
provides the necessary stiffness, being able to support the force
placed upon it and to withstand a much higher temperature than the
surface of the roller where there is an internal heating source.
Deposited above the support 116 is a resilient layer, also termed
the base cushion 113, which is characterized in the art as a
"cushion" layer with a function to accommodate the displacement for
the fusing nip. Deposited above the base cushion layer 113 is a tie
layer 114, which can be made of Viton, fluoroelastomer, or other
fluoropolymer, such as fluorocarbon thermoplastic copolymer and
mixtures thereof. The outermost layer 112, is a toner release
layer, which comprises the fluoropolymer resins, including PTFE,
PFA, and FEP, etc. and blends thereof, deposited on the tie layer
114.
Referring now to the accompanying drawing, FIG. 2 shows a preferred
embodiment of the fuser station, inclusive of the fuser roller
structure 200. The rotating fuser roller 110 moving in the
direction indicated by arrow A includes a plurality of layers
disposed about the axis of rotation; the plurality of the layers
including a cylindrical core member 116 of high stiffness material,
such as aluminum or steel, a relatively thick compliant
base-cushion layer (BCL) 113, formed or molded on the core with
perfect bondage at the interface, a seamless and relatively thin
Viton layer 114, coated on top of the BCL 113, with perfect bondage
at the interface, and a seamless and relatively thin topcoat 112,
of relatively stiffer material such as PFA than the elastomeric
materials, coated on top of the Viton layer 114, with perfect
bondage at the interface. The PFA topcoat is a thermally resistant
layer used for release of the substrate from the fusing member
110.
The surface of the fuser roller 110 can be externally heated by
heater rollers, 140 and 142, which are of incandescent or ohm-rated
heating filament 141 and 143, or internally heated by the
incandescent or ohm-rated heating filament 117, or heated by the
combination of both external heater rollers, 140 and 142, and
internally heating incandescent or ohm-rated filament 117. A
counteracting pressure roller 130 rotating in the direction A',
countering the fuser roller rotating direction A forms a fusing nip
300 with the fuser roller 110 made of a plurality of complaint
layers. An image-receiving substrate 212, generally paper, carrying
unfused toner 211, i.e., fine thermoplastic powder of pigments,
facing the fuser roller 110 is shown approaching the fusing nip
300. The substrate is fed by employing well know mechanical
transports (not shown) such as a set of rollers or a moving web for
example. The fusing station is preferable driven by one roller, for
instance the fusing roller, 110, with pressure roller 130 and
optional heater rollers, 140 and 142, being driven rollers.
The fuser member can be a pressure or fuser plate, pressure or
fuser roller, a fuser belt or any other member on which a release
coating is desirable. The support for the fuser member can be a
metal element with or without additional layers adhered to the
metal element. The metal element can take the shape of a
cylindrical core, plate or belt. The metal element can be made of,
for example, aluminum, stainless steel or nickel. The surface of
the metal element can be rough, but it is not necessary for the
surface of the metal element to be rough to achieve good adhesion
between the metal element and the layer attached to the metal
element. The additional support layers adhered to the metal element
are layers of materials useful for fuser members, such as, silicone
rubbers, fluoroelastomers and primers.
In one preferred embodiment of the invention, the support is a
metal element coated with an adhesion promoter layer. The adhesion
promoter layer can be any commercially available material known to
promote the adhesion between silicone rubber and metal, such as
silane coupling agents, which can be either epoxy-functionalized or
amine-functionalized, epoxy resins, benzoguanamineformaldehyde
resin crosslinker, epoxy cresol novolac, dianilinosulfone
crosslinker, polyphenylene sulfide polyether sulfone, polyamide,
polyimide and polyamide-imide. Preferred adhesion promoters are
epoxy-functionalized silane coupling agents. The most preferable
adhesion promoter is a dispersion of Thixon.TM. 300, Thixon.TM. 311
and triphenylamine in methyl ethyl ketone. The Thixon.TM. materials
are supplied by Morton Chemical Co.
In another preferred embodiment of the invention, the support is a
metal element with one or more resilient layer formed on said core
member comprising an elastomer base cushion layers. The base
cushion layer or layers can be of known materials for fuser member
layers such as, one or more layers of silicone rubbers,
fluorosilicone rubbers, or any of the same materials that can be
used to form elastomer layers. Preferred silicone rubber layers are
polymethyl siloxanes, such as EC-4952 (condensation cured silicone
rubber), S5100 (additional cured silicone rubber), sold by Emerson
Cummings or Silastic.TM. J or E sold by Dow Coming or X-34-1284,
X-34-2045 sold by ShinEtsu Company. Preferred fluorosilicone
rubbers include polymethyltrifluoropropylsiloxanes, such as
Sylon.TM. Fluorosilicone FX11293 and FX11299 sold by 3M.
In cases where it is intended that the fuser member be heated by an
internal heater, it is desirable that the outer layer have a
relatively high thermal conductivity, so that the heat can be
efficiently and quickly transmitted toward the outer surface of the
fuser member that will contact the toner intended to be fused.
Depending upon relative thickness, it is generally also very
desirable for the base cushion layer and any other intervening
layers to have a relatively high thermal conductivity.
The thickness and composition of the base cushion and release
layers can be chosen so that the base cushion layer provides the
desired resilience to the fuser member and the release layer can
flex to conform to that resilience. Usually, the release layer is
thinner than the base cushion layer. For example, cushion layer
thicknesses in the range from about 1.0 mm to about 10.0 mm have
been found to be appropriate for various applications. In some
embodiments of the present invention the base cushion layer is
about 5.0 mm thick and the outer layer is from about 5 .mu.m to
about 50 .mu.m thick.
According to the current invention, suitable materials for the base
cushion layer include any of a wide variety of materials previously
used for base cushion layers, such as the condensation cured
polydimethylsiloxane marketed as EC4952 by Emerson Cuming. Another
example of a additional cured silicon rubber base cushion layer is
marked as S5100 by Emerson Cuming. An example of an addition cured
silicone rubber is X-34-1284, from ShinEtsu Company, which is
applied over a silane primer X-33-173 or X-33-156-20, also
obtainable from ShinEtsu Company.
In a particular embodiment of the invention, the base cushion is
resistant to cyclic stress induced deformation and hardening.
Examples of suitable materials to reduce cyclic stress induced
deformation and hardening are filled condensation-crosslinked PDMS
elastomers, disclosed in U.S. Pat. No. 5,269,740 (copper oxide
filler), U.S. Pat. No. 5,292,606 (zinc oxide filler), U.S. Pat. No.
5,292,562 (chromium oxide filler), U.S. patent application Ser. No.
08/167,584 (tin oxide filler) and U.S. patent application Ser. No.
08/159,013 (nickel oxide filler). These materials all show
reasonable thermal conductivities and much less change in hardness
and creep than EC4952 or the PDMS elastomer with aluminum oxide
filler. Additional suitable base cushions are disclosed in U.S.
patent application Ser. No. 08/268,136, entitled "Zinc Oxide Filled
Diphenylsiloxane-Dimethylsiloxane Fuser Roll for Fixing Toner to a
Substrate", U.S. patent application Ser. No. 08/268,141, entitled
"Tin Oxide Filled Diphenylsiloxane-Dimethylsiloxane Fuser Roll for
Fixing Toner to a Substrate", U.S. patent application Ser. No.
08/268,131, entitled "Tin Oxide Filled
Dimethylsiloxane-Fluoroalkylsiloxane Fuser Roll for Fixing Toner to
a Substrate". The disclosures of the patents and patent
applications mentioned in this paragraph are hereby incorporated
herein by reference.
The support of the fuser member, which is usually cylindrical in
shape, can be formed from any rigid metal or plastic substance.
Because of their generally high thermal conductivity, metals are
preferred when the fuser member is to be internally heated.
Suitable support materials include, e.g., aluminum, steel, various
alloys, and polymeric materials such as thermoset resins, with or
without fiber reinforcement. The support which has been conversion
coated and primed with metal alkoxide primer in accordance with
U.S. Pat. No. 5,474,821, the disclosure of which is incorporated
herein by reference.
The fuser member is mainly described herein in terms of embodiments
in which the fuser member is a fuser roll having a support, a base
cushion layer overlying the support, a fluoroelastomer tie layer,
and an outer layer superimposed on the tie layer. The invention is
not, however, limited to a roll, nor is the invention limited to a
fusing member having a support bearing two layers: the base cushion
layer and the outer layer. The fuser member of the invention can
have a variety of outer configurations and layer arrangements known
to those skilled in the art. For example, the base cushion layer
may be eliminated, or the outer layer described herein could be
overlaid by one or more additional layers.
The base cushion layer may be adhered to the metal element via a
base cushion primer layer. The base cushion primer layer can
include a primer composition which improves adhesion between the
metal element and the material used for the base cushion layer. If
the base cushion layer is a fluoroelastomer material, the adhesion
promoters described above can be used as the base cushion primer
layer. Other primers for the application of fluorosilicone rubbers
and silicone rubbers to the metal element are known in the art.
Such primer materials include silane coupling agents such as
X-33-176 or X-33-156-10 sold by ShinEtsu Company, which can be
either epoxy-functionalized or amine-functionalized, epoxy resins,
benzoguanamineformaldehyde resin crosslinker, epoxy cresol novolac,
dianilinosulfone crosslinker, polyphenylene sulfide polyether
sulfone, polyamide, polyimide and polyamide-imide.
The inclusion of a base cushion layer on the metal element of the
support increases the compliancy of the fuser member. By varying
the compliancy, optimum fuser members and fuser systems can be
produced. The variations in the compliancy provided by optional
base cushion layers are in addition to the variations provided by
just changing the thickness or materials used to make the
fluoroelastomer layer and/or fluoropolymer resin layer. The
presently preferred embodiment in a fuser roller system is to have
a very compliant fuser roller and a non-compliant or less compliant
pressure roller. In a fuser belt system it is preferred to have a
compliant pressure roller and a non-compliant or less compliant
belt. Although the above are the presently preferred embodiments,
fuser systems and members including plates, belts and rollers can
be made in various configurations and embodiments wherein at least
one fuser member is made according to this invention.
The fluoroelastomer layer can comprise copolymers of vinylidene
fluoride and hexafluoropropylene, copolymers of tetrafluoroethylene
and propylene, terpolymers of vinylidene fluoride,
hexafluoropropylene and tetrafluoroethylene, terpolymers of
vinylidene fluoride, tetrafluoroethylene and
perfluoromethylvinylethyl, and terpolymers of vinylidene fluoride,
tetrafluoroethylene, and perfluoromethylvinylether. Specific
examples of fluoroelastomers which are useful in this invention are
commercially available from E. I. DuPont de Nemours and Company
under the trade names Kalrez .TM., and Viton.TM. A, B, G, GF and
GLT, and from 3M Corp. under the trade names Fluorel.TM. FC 2174,
2176 and FX 2530 and FLS 2640 and FE 5832 and Aflas.TM.. Additional
vinylidene fluoride based polymers useful in the fluoroelastomer
layer are disclosed in U.S. Pat. No. 3,035,950, the disclosure of
which is incorporated herein by reference. Mixtures of the
foregoing fluoroelastomers may also be suitable. Although it is not
critical in the practice of this invention, the number-average
molecular weight range of the fluoroelastomers may vary from a low
of about 10,000 to a high of about 200,000. In the preferred
embodiments, vinylidene fluoride-based fluoroelastomers have a
number-average molecular weight range of about 50,000 to about
100,000.
A preferable material for the fluoroelastomer layer is a compounded
mixture of a fluoroelastomer polymer, a curing material, and
optional fillers. The curing material can include curing agents,
crosslinking agents, curing accelerators and fillers or mixtures of
the above. Suitable curing agents for use in the process of the
invention include the nucleophilic addition curing agents as
disclosed, for example, in the patent to Seanor, U.S. Pat. No.
4,272,179, incorporated herein by reference. Exemplary of a
nucleophilic addition cure system is one comprising a bisphenol
crosslinking agent and an organophosphonium salt as accelerator.
Suitable bisphenols include 2,2-bis(4-hydroxyphenyl)
hexafluoropropane, 4,4-isopropylidenediphenol and the like.
Although other conventional cure or crosslinking systems may be
used to cure the fluoroelastomers useful in the present invention,
for example, free radical initiators, such as an organic peroxide,
for example, dicumylperoxide and dichlorobenzoyl peroxide, or
2,5-dimethyl-2,5-di-t-butylperoxyhexane with triallyl cyanurate,
the nucleophilic addition system is preferred. Suitable curing
accelerators for the bisphenol curing method include
organophosphonium salts, e.g., halides such as benzyl
triphenylphosphonium chloride, as disclosed in U.S. Pat. No.
4,272,179 cited above.
The fluoroelastomer also can include fluoropolymer resin filler.
Fluoropolymer resin filler are added to polymeric compositions from
10 to 100 pph based on the weight of the fluoroelastomer layer to
provide added adhesion strength and mechanical strength to a
surface layer. In the fluoroelastomer layer of the fuser member of
this invention, inclusion of the inert filler is preferred.
Omission of the inert filler will reduce the adhesive strength of
the fluoroelastomer layer to the top layer. Suitable fluoropolymer
resin fillers which consist of a fluoropolymer material, such as a
semicrystalline fluoropolymer or a semicrystalline fluoropolymer
composite. Such materials include polytetrafluoroethylene (PTFE),
polyperfluoroalkoxy-tetrafluoroethylene (PFA), polyfluorinated
ethylene-propylene (FEP), poly(ethylenetetrafluoroethylene),
polyvinylfluoride, polyvinylidene fluoride,
poly(ethylene-chloro-trifluoroethylene),
polychlorotrifluoroethylene and mixtures of fluoropolymer
resins.
The fluoroelastomer can include inert filler. Inert fillers are
frequently added to polymeric compositions to provide added
strength and abrasion resistance to a surface layer. In the
fluoroelastomer layer of the fuser member of this invention,
inclusion of the inert filler is optional. Omission of the inert
filler does not reduce the adhesive strength of the fluoroelastomer
layer. Suitable inert fillers which are optionally used include
mineral oxides, such as alumina, silica, titania, and carbon of
various grades.
Nucleophilic addition-cure systems used in conjunction with
fluoroelastomers can generate hydrogen fluoride and thus acid
acceptors may be added as fillers. Suitable acid acceptors include
Lewis bases such as lead oxide, magnesium oxide, such as
Megalite.TM. D and Y supplied by Merck & Co., calcium
hydroxide, such as C-97, supplied by Fisher Scientific Co., zinc
oxide, copper oxide, tin oxide, iron oxide and aluminum oxide which
can be used alone or as mixtures with the aforementioned inert
fillers in various proportions. The most preferable fluoroelastomer
layer material comprises a compounded mixture of 100 parts
Viton.TM. A, from 2 to 9 parts 2,2-bis(4-hydroxyphenyl)
hexafluoropropane, commercially available as Cure.TM. 20, from 2 to
10 parts benzyl triphenylphosphonium chloride, commercially
available as Cure 30.TM., from 5 to 30 parts lead oxide and from 0
to 30 parts Thermax.TM. (carbon black), mechanically compounded at
room temperature on a two roll mill until it forms a uniform
mixture. Cure.TM. 20 and Cure.TM. 30 are products of Morton
Chemical Co. Thermax.TM. is a product of R. T. Vanderbilt Co., Inc.
This compounded mixture can either be compression molded onto the
support, or dispersed in solvent for dip-, ring- or spray-coating
onto the support. If ring-coating is used to apply this compounded
mixture to the support, then it is preferable to add a small amount
of aminosiloxane polymer to the formulation described above, while
compounding the fluoroelastomer material. For additional
information on this fluoroelastomer composite material, see U.S.
Pat. No. 4,853,737, which is incorporated herein by reference.
The fluoroelastomer layer can also be an interpenetrating network
of fluoroelastomer and a silicone polymer. An interpenetrating
network coating composition can be obtained by mechanically
compounding fluoroelastomer polymer, functionalized siloxane,
fluorocarbon curing materials and optional acid acceptors or other
fillers to form a uniform mixture suitable for compression molding
or solvent coating after dispersing the composite in a solvent. The
fluoroelastomer polymers, curing materials, curing agents, curing
accelerators, acid acceptors and other fillers can be selected from
those previously described above. The functionalized siloxane is
preferably a polyfunctional poly(C.sub.1-6 alkyl)phenyl siloxane or
polyfunctional poly(C.sub. 1-6 alkyl)siloxane. Preferred siloxanes
are heat-curable, however peroxide-curable siloxanes can also be
used with conventional initiators. Heat curable siloxanes include
the hydroxy-functionalized organopolysiloxanes belonging to the
classes of silicones known as "hard" and "soft" silicones.
Preferred hard and soft silicones are silanol-terminated
polyfunctional organopolysiloxanes.
Exemplary hard and soft silicones are commercially available or can
be prepared by conventional methods. Examples of commercially
available silicones include DC6-2230 silicone and DC-806A silicone
(sold by Dow Corning Corp.), which are hard silicone polymers, and
SFR-100 silicone (sold by General Electric Co.) and EC-4952
silicone (sold by Emerson Cummings Co.), which are soft silicone
polymers. DC6-2230 silicone is characterized as a
silanol-terminated polymethyl-phenylsiloxane copolymer containing
phenyl to methyl groups in a ratio of about 1 to 1, difunctional to
trifunctional siloxane units in a ratio of about 0.1 to 1 and
having a number-average molecular weight between 2,000 and 4,000.
DC-806A silicone is characterized as a silanol-terminated
polymethylphenylsiloxane copolymer containing phenyl to methyl
groups in a ratio of about 1 to 1 and having difunctional to
trifunctional siloxane units in a ratio of about 0.5 to 1. SFR-100
silicone is characterized as a silanol- or
trimethylsilyl-terminated polymethylsiloxane and is a liquid blend
comprising about 60 to 80 weight percent of a difunctional
polydimethylsiloxane having a number-average molecular weight of
about 90,000 and 20 to 40 weight percent of a polymethylsilyl
silicate resin having monofunctional (i.e. SiO.sub.2) repeating
units in an average ratio of between about 0.8 and 1 to 1, and
having a number-average molecular weight of about 2,500. EC-4952
silicone is characterized as a silanol-terminated
polymethylsiloxane having about 85 mole percent of difunctional
dimethylsiloxane repeating units, about 15 mole percent of
trifunctional methylsiloxane repeating units and having a
number-average molecular weight of about 21,000.
Preferred fluoroelastomer-silicone interpenetrating networks have
ratios of silicone to fluoroelastomer polymer between about 0.1 and
1 to 1 by weight, preferably between about 0.2 and 0.7 to 1. The
interpenetrating network is preferably obtained by mechanically
compounding, for example, on a two-roll mill a mixture comprising
from about 40 to 70 weight percent of a fluoroelastomer polymer,
from 10 to 30 weight percent of a curable polyfunctional
poly(C.sub.1-6 alkyl)phenylsiloxane or poly(C.sub.1-6
alkyl)siloxane polymer, from 1 to 10 weight percent of a curing
agent, from 1 to 3 weight percent of a curing accelerator, from 5
to 30 weight percent of an acid acceptor type filler, and from 0 to
30 weight percent of an inert filler.
When a fluoroelastomer-silicone interpenetrating network is the
fluoroelastomer layer material, the support is coated by
conventional techniques, usually by compression molding or solvent
coating. The solvents used for solvent coating include polar
solvents, for example, ketones, acetates and the like. Preferred
solvents for the fluoroelastomer based interpenetrating networks
are the ketones, especially methyl ethyl ketone and methyl isobutyl
ketone. The dispersions of the interpenetrating networks in the
coating solvent are at concentrations usually between about 10 to
50 weight percent solids, preferably between about 20 to 30 weight
percent solids. The dispersions are coated on the support to give a
10 to 100 micrometer thick sheet when cured.
Curing of the interpenetrating network is carried out according to
the well known conditions for curing fluoroelastomer polymers
ranging, for example, from about 12 to 48 hours at temperatures of
between 50.degree. C. to 250.degree. C. Preferably, the coated
composition is dried until solvent free at room temperature, then
gradually heated to about 230.degree. C. over 24 hours, then
maintained at that temperature for 24 hours.
Additional information on fluoroelastomer-silicone polymer
interpenetrating networks can be found in U.S. patent application
Ser. No. 122,754 filed Sep. 16, 1993, which is a continuation of
U.S. patent application Ser. No. 940,929, filed Sep. 4, 1992. Also
see, U.S. patent application Ser. No. 940,582, filed Sep. 4, 1992.
These three patent applications are assigned to the Eastman Kodak
Company. The disclosures of these patent applications are
incorporated herein by reference.
The fluoroelastomer layer can also include a fluorocarbon
thermoplastic copolymer comprising a copolymer of vinylidene
fluoride and hexafluoropropylene, the cured fluorocarbon
thermoplastics random copolymer having subunits of:
--(CH.sub.2CF.sub.2)x--, --(CF.sub.2CF(CF.sub.3))y--, and
--(CF.sub.2CF.sub.2)z--, wherein
x is from 1 to 40 or 60 to 80 mole percent,
z is greater than 40 to no more than 89 mole percent, and
y is such that x+y+z equals 100 mole percent.
Suitable fluorocarbon thermoplastic random copolymers are available
commercially. In a particular embodiment of the invention, a
vinylidene fluoride-co-tetrafluoroethylene co-hexafluoropropylene,
which can be represented as --(VF)(75) -(TFE) (10) --(HFP)(25)-,
was employed. This material is marketed by Hoechst Company under
the designation "THV Fluoroplastics" and is referred to herein as
"THV". In another embodiment of the invention, a vinylidene
fluoride-co-tetrafluoroethylene-co-hexafluoropropylene, which can
be represented as --(VF)(42)-(TFE)(10) --(HFP)(58)-, was used. This
material is marketed by Minnesota Mining and Manufacturing, St.
Paul, Minn., under the designation "3M THV" and is referred to
herein as "THV-200". Other suitable uncured vinylidene
fluoride-cohexafluoropropylenes and vinylidene
fluoride-co-tetrafluoroethylene-cohexafluoropropylenes are
available, for example, THV-400, THV-500 and THV-300.
In general, THV Fluoroplastics are set apart from other
melt-processable fluoroplastics by a combination of high
flexibility and low process temperature. With flexural modulus
values between 83 Mpa and 207 Mpa, THV Fluoroplastics are the most
flexible of the fluoroplastics.
The molecular weight of the uncured polymer is largely a matter of
convenience; however, an excessively large or excessively small
molecular weight would create problems, the nature of which are
well known to those skilled in the art. In a preferred embodiment
of the invention the uncured polymer has a number average molecular
weight in the range of about 100,000 to 200,000.
The fluoropolymner resin outer layer includes a fluoropolymer
material, such as a semicrystalline fluoropolymer or a
semicrystalline fluoropolymer composite. Such materials include
polytetrafluoroethylene (PTFE),
polyperfluoroalkoxy-tetrafluoroethylene (PFA), polyfluorinated
ethylene-propylene (FEP), poly(ethylenetetrafluoroethylene),
polyvinylfluoride, polyvinylidene fluoride,
poly(ethylene-chloro-trifluoroethylene),
polychlorotrifluoroethylene and mixtures of fluoropolymer resins.
Some of these fluoropolymer resins are commercially available from
DuPont as Teflon.TM. or Silverstone.TM. materials.
The preferred fluoropolymer resin layer is a
polyperfluoroalkoxy-tetrafluoroethylene (PFA), commercially
available from DuPont under the trade name Teflon.TM. 855P322-32,
Teflon.TM. 855P322-53, Teflon.TM. 855P322-55, Teflon.TM.
855P322-57, Teflon.TM. 855P322-58 and Teflon.TM. 857-210.
Particularly Teflon.TM. 855P322-53; Teflon.TM. 855P322-57, and
Teflon.TM. 855P322-58 are preferred because it is durable, abrasion
resistant and forms a very smooth layer. The
polyperfluoroalkoxy-tetrafluoroethylene (PFA) further comprises
filler particles such as silicone carbide, aluminum silicate,
carbon black, zinc oxide, tin oxide etc.
The thicknesses of the layers of the fuser members of this
invention can vary depending on the desired compliancy or
non-compliancy of a fuser member. The preferred thicknesses of the
layers for a fuser member having a base cushion layer as part of
the support are as follows: the base cushion primer layer may be
between 0.1 and 1 micron; the base cushion layer may be between 1
and 10 mm, the fluoroelastomer layer may be between 10 and 500
micron; and the fluoropolymer resin layer may be between 5 and 50
microns. The preferable thicknesses for the layers of a fuser
member with base cushion layer (resilient layer) as part of the
support are as follows: the adhesion promoter may be between 0.3
and 1 mils; the base cushion layer maybe between 2 and 6 mm; the
fluoroelastomer layer may be between 10 and 50 micron; and the
fluoropolymer resin layer may be between 5 and 30 micron.
The compositions of the above-described layers of the fuser member
may optionally contain additives or fillers such as aluminum oxide,
iron oxide, magnesium oxide, silicon dioxide, titanium dioxide,
calcium hydroxide, lead oxide, zinc oxide, copper oxide and tin
oxide to increase the thermal conductivity or the hardness of the
layers. Pigments may be added to affect the color. Optional
adhesive materials and dispersants may also be added.
In one embodiment of the invention, the support is a metal element
and an adhesion promoter for a fluoroelastomer layer. In another
embodiment of the invention the support includes a adhesion
promoter layer and one or more base cushion layers with additional
primer layers between the base cushion layers where necessary. The
methods of making some of the embodiments of this invention will be
described in more detail.
One embodiment of the invention, the fuser member without a base
cushion layer can be prepared as follows:
Firstly, the support is prepared. A metal element is cleaned and
dried. Any commercial cleaner or known solvent, for example
isopropyl alcohol, which will remove grease, oil and dust can be
used for this purpose. The support is further prepared by applying
to the metal element the adhesion promoter layer. The adhesion
promoter may be applied to the metal element by any method that
provides a uniform coating. Examples of such methods include
wiping, brushing, or spray-, ring- or dip-coating the material onto
the metal support. The adhesion promoter is dried and cured
typically in an oven at temperatures between about 320.degree. F.
and 350.degree. F. The most preferable adhesion promoter is a
dispersion of Thixon.TM. 300, Thixon.TM. 311 and triphenylamine in
methyl ethyl ketone. The Thixon.TM. materials are supplied by
Morton Chemical Co. Secondly, the fluoroelastomer layer is applied
to the adhesion promoter layer usually by compression-molding,
extrusion-molding, or blade-, spray-, ring- or dip-coating the
fluoroelastomer layer onto the support. The fluoroelastomer layer
is then cured typically in an oven at temperatures between about
390.degree. F. and 500.degree. F. Thirdly, the fluoropolymer resin
layer can be applied to the primer layer by the same methods for
applying the fluoroelastomer layer. It is not necessary to dry the
primer layer before applying the fluoropolymer resin layer.
Preferably, the fluoropolymer resin layer is applied by
ring-coating an aqueous emulsion of a fluoropolymer resin over the
primer layer. Fourthly, the fuser member is placed in an oven
typically at temperatures between about 600.degree. F. and
700.degree. F. to cure the fluoropolymer resin layer. (The
specified temperature ranges can vary depending upon the material
to be cured and the curing time.)
Other embodiments of the invention have a base cushion layer as
part of the support. For example, to make a coated fuser member
with a support including a metal element, silicone rubber primer
layer, and a condensation cure silicone rubber layer, and then the
fluoroelastomer layer, and fluoropolymer resin layer, the method is
as follows: Firstly, the metal element is cleaned and dried as
described earlier. Secondly, the metal element is coated with a
layer of a known silicone rubber primer, selected from those
described earlier. A preferred primer for a condensation cure
silicone rubber base cushion layer is GE 4044 supplied by General
Electric. Thirdly, the silicone rubber layer is applied by an
appropriate method, such as, blade-coating, ring-coating,
injection-molding or compression-molding the silicone rubber layer
onto the silicone rubber primer layer. A preferred condensation
cure polydimethyl siloxane is EC-4952 produced by Emerson Cummings.
Fourthly, the silicone rubber layer is cured, usually by heating it
to temperatures typically between 410.degree. F. and 450.degree. F.
in an oven. Fifthly, the silicone rubber layer undergoes corona
discharge treatment usually at about 750 watts for 90 to 180
seconds. From here the process of applying and curing the
fluoroelastomer layer, and fluoropolymer resin layer described
above is followed.
In yet other embodiments of the invention with a base cushion layer
as part of the support, the process is modified as follows. If the
base cushion layer is an addition cure silicone rubber, the
preferred silicone primer X-33-176 supplied by ShinEtsu Company is
applied to the metal element. Then, the preferred additional cure
silicone rubber X-34-1284 supplied by ShinEtsu Company is applied,
for example, by injection-molding. The silicone rubber layer is
then cured. If the base cushion layer is a fluorosilicone
elastomer, the metal element is primed with a known silicone
primer, then the fluorosilicone elastomer layer is applied, usually
by compression-molding and cured. If a fluoroelastomer-silicone
interpenetrating network or other additional fluoroelastomer
material is used as the base cushion layer or layers, an adhesion
promoter appropriate for a fluoroelastomer layer is applied to the
metal element, the fluoroelastomer base cushion layer is applied to
the base cushion primer layer and cured. If the base cushion layer
is a fluoroelastomer material it is not necessary to cure, prime or
to corona discharge treat the base cushion fluoroelastomer layer
before application of the fluoroelastomer layer to it.
There are optional sandblasting, grinding and polishing steps. As
stated earlier, it is not necessary to sandblast the metal element,
because it is not required for good adhesion between the metal
element and the adjacent layer. However, the fluoroelastomer layer
and additional base cushion layer or layers, if any, may be ground
during the process of making the fuser members. These layers may be
mechanically ground to provide a smooth coating of uniform
thickness that sometimes may not be the result when these layers
are applied to the support, especially by the processes of
compression-molding or blade-coating.
Any kind of known heating method can be used to cure or sinter the
layers onto the fuser member, such as convection heating, forced
air heating, infrared heating, and dielectric heating.
The fuser members produced in accordance with the present invention
are useful in electrophotographic copying machines to fuse
heat-softenable toner to a substrate. This can be accomplished by
contacting a receiver, such as a sheet of paper, to which toner
particles are electrostatically attracted in an imagewise fashion,
with such a fuser member. Such contact is maintained at a
temperature and pressure sufficient to fuse the toner to the
receiver. Because these members are so durable they can be cleaned
using a blade, pad, roller or brush during use. And, although it
may not be necessary because of the excellent release properties of
the fluoropolymer resin layer, release oils may be applied to the
fuser member without any detriment to the fuser member.
The following examples illustrate the preparation of the fuser
members of this invention.
EXAMPLE 1
A coated roller including, in order, a support, a base cushion
primer layer and a silicone rubber layer, and a fluoroelastomer
layer, a PFA fluoropolymer resin layer was prepared.
A steel cylindrical core with a 3.5 inch outer diameter and 15.2
inch length that was blasted with glass beads and cleaned and dried
with dichloromethane was uniformly spray-coated with an adhesion
promoter ShinEtsu X-33-176 to a uniform thickness of from 0.1 to
0.2 mil. The adhesion promoter was air dried for 15 minutes and
placed in a convection oven at 325.degree. F. for 45 minutes. A
silicone base cushion layer is then applied to the treated core.
The preferred addition cure silicone rubber X-34-1284 supplied by
ShinEtsu Co is applied, for example, by injection-molding. The
silicone rubber then cured 24 hrs at room temperature, and post
cured 3 hrs at 200.degree. C. in a convection oven. The resulting
thickness of the base cushion layer was 220 mil. The
fluoroelastomer coating was prepared by compounding 100 parts of
Fluorel.TM. 2640, 4 parts Cure.TM. 50, 3 parts magnesium oxide, 6
parts calcium hydroxide, 10 parts Thermax and 50 parts FEP are
dissolved into a MEK solution to formed a 25 weight percent solid
solution. A portion of the resulting solution was ring coated onto
a core with the silicone base cushion layer as previously
described, air dried 1 hour. The conditions for the post-cure were
a 24 hour ramp to 232.degree. C. and 24 hours at 232.degree. C. The
resulting fluoroelastomer layer had 25 micron in thickness. An
outer layer of Teflon 855P322-53, a PFA fluoro resin about 0.5 mils
thick was ring-coated onto the fluoroelastomer layer. The fuser
member was then placed in a convection oven at 700.degree. F. for
approximately 10 minutes to sinter the PFA Teflon.TM..
The roller had excellent adhesion between the layers. A peel
strength test was performed. Typically to perform a peel strength
test of a multi-layer fuser member, the top layer is cut and
clamped into an Instron apparatus and the force required to peel
the PFA top layer from the adjacent layer on the roller is
measured. For the roller made according to Example 1, the adhesion
strength between the fluoropolymer resin layer and the
fluoroelastomer layer is listed in Table 1.
TABLE-US-00001 TABLE 1 Adhesion test Experimental Adhesion Example
PFA topcoat Primer Viton Tie Layer Base Cushion (gmw) E-1
855P322-53 None Fluoroelastomer X-34-1284 73 C-1 855P322-53 33 None
X-34-1284 <72 C-2 855P322-32 None None X-34-1284 <32 *The
minimum required strength of adhesion for the fuser member outer
layer was 32.
Comparative Example 1
A coated roller consisting of, in order, a support, a base cushion
primer layer and a silicone rubber layer, and a primer layer
comprising perfluoroalkoxy resin and
trifluoroethylene-perfluoroethyl ether-perfluoroethylene vinyl
phosphate, and a PFA fluoropolymer resin outer layer was
prepared.
Example 1 was repeated except the fluoroelastomer layer was used
instead of the primer layer, DuPont Teflon.TM. 855P322-33
comprising perfluoroalkoxy resin and
trifluoroethylene-perfluoroethyl ether-perfluoroethylene was
ring-coated on the silicone base cushion.
Comparative Example 2
A coated roller consisting of, in order, a support, a base cushion
primer layer and a silicone rubber layer and a PFA fluoropolymer
resin outer layer was prepared.
Example 1 was repeated except the fluoroelastomer layer was used as
a tie layer. An outer layer DuPont Teflon.TM. 855P322-32 consisting
of polytetrafluoroethylene,
polyperfluoroalkoxy-tetrafluoroethylene, polyfluorinated
ethylene-propylene, and blends thereof was ring-coated on the
silicone base cushion.
The same peel test of the adhesion was performed on the rollers
prepared in Example 1 and Example 2. Results of the tests the
adhesion strength between the fluoropolymer resin layer and the
silicone rubber layer are listed in Table 1.
Roller Life Test
The life tests of the rollers prepared in Example 1 and Example 2
were performed by putting the roller in the Nexpress 2100 machine.
The results of the tests are listed in Table 2.
Roller life test is to subject the fuser member to a surface
temperature ranging from 175.degree. C. to 180.degree. C. during
printing. The surface temperature of the fuser member is maintained
by either the internal heating and the contacting external heater
rollers, preferably both. The temperature of the external heater
rollers ranges from 230.degree. C. to 250.degree. C. and the
contacting nip width between the external heater rollers and the
fuser member ranges from 10% to 20% of the heat roller diameter.
The substrate (paper) used is of thickness 330 micron and of a
planar density of 300 grams per meter square. The nip width between
the fuser member and the counteracting pressure roller to fuse the
toner was set at 20% of the diameter of the fuser member with a
range of +/-1%. The substrate (paper) size can be Tabloid, i.e.,
11''.times.17'', or similar. The toner amount on the substrate was
set near 0 to simulate a stressed printing condition for the
topcoat. The printing speed ranges from 90 to 110 ppm. The fuser
member assembly is inspected directly and with print or so to
detect the emergence of surface anomaly. Inspection includes inside
paper path and outside paper path of the fuser member surface.
Record of the fuser member condition is kept every 1000 to 2000 A4
equivalent sheets.
TABLE-US-00002 TABLE 2 Roller life test Experimental Life (A4 eqv.
Example PFA topcoat Primer Viton Tie Layer Base Cushion pages) E-1
855P322-53 None Fluoroelastomer X-34-1284 >37,000 C-1 855P322-53
33 None X-34-1284 >20,000.sup.# *The roller materials cracked in
the beginning few prints. .sup.#Outside paper path showing
cracks.
The roller of the current invention from Example 1 had superior
performance than the rollers prepared from Comparative Example 1
and Comparative Example 2. The result of the adhesion test and the
roller life test of the inventive roller consistently demonstrated
that the rollers had excellent adhesion strength and durability
than the prepared rollers without the fluoroelastomer tie layer.
Further, from the roller life test, the fluoroelastomer tie layer
of the inventive roller prevent the degradation of the silicone
base cushion layer, e.g., cracking under high temperature condition
due to the heat from the external heating rollers, particularly the
area outside the paper path, and the sintering of the fluoropolymer
resin PFA topcoat.
The invention has been described in detail with particular
reference to certain preferred embodiments thereof, but it will be
understood that variations and modifications can be effected within
the spirit and scope of the invention.
* * * * *